Crucible holder and crucible



Feb. 22, 1949. J. FREI, JR 2,462,259

GRUCIBLE HOLDER AND CRUCIBLE Filed Jan. 20, 1945 Crucible into a suitable mold. commonly used for melting the 7metal are rather Patented Feb. 22, 1949 UNITED S TATES PAT ENT v F FICE ('RUCIBLET HOLDER ANDI vCRUCIBLEl John Frei, Jr., Chicago, Ill.

Application January 20, 1945,*"Se`rial-No. 573,746

,5 Claims.

This 'invention-relatesto Casting `apparatus,

and'has' to ydo with crucibles intended particularly for use in centrifugalffcasting.

tisi known,particularly in the dental and jewelry'elds to Cast'varticles centriiugally by melting the metal in a Crucible and projecting themlten metal, by centrifugal force;-from=the The crucibles expensive and subject to Cracking and breaking `after being "in use for'a short timeand are not rtity production, this Crucible ComprisingA an outer body or holder, which may be termed the secondary Crucible, and an `inner .member in the nature ,of a liner, whichv constitutes vthe primary Crucible .in which the metal vor other material is melted. 4The secondary Crucible` or bodyris formed in two sectionsthelower of which contains the'inner Crucible, ther two sectionsbeing provided with ,grooved flanges whereby the assembled Crucible may readily be mounted upon supporting arid aligning vflanges of, a supporting structure of the centrifugal. ,machine The Vinner or primary 4Crucibleis open at its top, so thatbyv removing theupper section ofthe outer Crucible or holder, thefmetalfcrfother materialV may be quickly placed within the .primary Crucible and the upper section` ci` the outer Crucible or 4holder may as ,quickly be replaced. r'The two sections of the 'outer structure have Cooperating shoulders or A,projections providing ua rclosure about the primary crucible to-guard against spillage of metal therefrom, and theY primary Crucible preferably 'is supportedi'inv the `lower-secticnrof the outer ycrucibleor -holder in'such manner as tobe out ofl Contact therewith fory the major .area-vof its `exterior surface, whichfasssts in ,-preventing excessi-ve heatingy of the outer Crucible and result -iantvcracking thereoL-Ithe-spacing.of Athe inner Crucible from the outer Crucible Aalso rendering possible the functioningbf the llatter for projecting the molten metal into the mold inthe event of breakingY or cracking of theinnercrucible. Further-objects-and advantages of .my invention will appear from .the detail description.

Y. InfitheV drawings: Figure lis aidiagrammatic plan view of acenv1; and

Figure 6 is a sectionalvlew, on an enlarged scale, taken'substantially on line 6--6 of Fgure 1.

In Figure l I have shown, `more or less diagrammatically, acentrifugal casting machine of -known type comprising disc I0 having associated means for-rotating itat high speedV about a vertical vaxisgto which -dlsC is secured an arm II Carrying anadjustable weight I-2 and provided at its outer end-with a handle I3. A second arm I4 ispivoted at I5-to arm II', and has adjustably mounted thereon'aY suitable Carriage 'I6 provided with a holder II appropriately vformed to receive and retain a circumferentially grooved flange I8 of aV cylindrical Crucible I9 formed of suitable refractory material. The Crucible I9, to be described more in detailn presently, is provided at itsouter end with anopening disposed to deliver the charge of moltenmetal to a mold 2U, which will also ybe described `more fully presently, mounted at its outer` end in a support 2I carried by arm'I4 and'resting, at 'its innerend, in support I'I, vspaced av short distance from the outer end'of Crucible I9. -Assuming that there is a proper Charge of molten metal in the crucible IS, by rotating disc I0 in the direction indicated Yby the arrow, and with it the arms. II and I4,

the molten metal is projected by centrifugal force from the Crucible I9 into the mold 2U, in which the. metal is permitted to set for producing the desired 'articlaas is known in the centrifugal casting art.

`which tapersto discharge opening 25 defined by receiving a shoulder 30 projecting upward fromv the upper face of lower section 23 and extending about' the recess therein, flange 29 providing with shoulder 3i! a closure about the melting chamber 24 and in cooperation with shoulder 3! restraining the upper section 22 against outward endwise movement relative to the lower section 23.

The lower section 23 is provided interiorly with spaced lengthwise ribs 3| defining between them spaces or channels which open into the outer end of the recess of this section.y An inner or primarycrucible 32 seats upon ribs 3|, within the recess of lower section'23, and is spaced by the ribs 3l from the surrounding wall of section 23. The primary crucible 32 is open at its top, as shown, and tapers at its youter portion to a discharge neck 33 extending through discharge opening 25, this neck being spaced a short distance above the bottom of the opening. The out- 4wardv taper of crucible 32 and the outward taper of the recess inlower section 23 of the secondary crucible provides cooperating shoulders which restrainthe primarycrucible 32 against outward movement relative to section 23, as will be understood. The primary crucible 32 is formed of suitable refractory material which may be either electrical conducting or non-conducting as conditions require. It may be rather thin, compared to the secondary crucible or holder, and comparatively inexpensive. Under ordinary conditions the primary cruciblemay be used a considerable number of times, and in event of cracking or breakagethereof, or when an objectionable amount of slag accumulates therein,f this primary crucible may be discarded and replaced by an unused crucible. The ribs 3l provide small area of contact between the primary crucible 3! and section 23 of the secondary crucible, reducing heat ilow from the primary crucible to the secondary .crucible and thereby avoiding excessive heating and resultant cracking or breakage of the secondary crucible. That is ofY importance in quantity production of `articles by centrifugal casting, since the secondary crucible is rather expensive and necessity for frequent replacement thereof would render vthe centrifugal casting of articles objectionably expensive. The primary crucible 32, on the other hand, is comparatively inexpensive andrnay be replaced without incurring .objectionable rexpense in the casting of the ar- ,when thesectionsof the secondary crucible are about properly assembled. Flange I8 .is provided with a circumferential groove `34 which snugly receives flange 35.0f holder I1, by means of which the sections 22 and 23 of the secondary crucible `are accurately aligned and the crucible I9, as a whole, is mounted on the holder I1 with its outer end spaced a short distance from the inner Yend of mold 20. v i n The mold 2U comprises a flask 36 of a suitable 4 heat resistant metal or alloy, such as stainless steel, within which there is a body 31 of refractory having formed therein a gate 33 opening through the inner end of the mold, this gate communicating with a casting cavity (not shown) formed in body 31. Preferably the mold 20 is produced in the manner disclosed in my copending application for Investing means and method, i'lled November 9, 1944, Serial No. 562,707, though it may be produced in any other suitable manner.

In the use of the crucible of my invention in centrifugal casting, the primary crucible 32 is placed within lower section 23 of the secondary crucible and the metal from' which the article is to be cast is placed in the primary crucible, conveniently in the form of a cube or block 39 of proper mass.v Conveniently that operation is performed after the lower section 23 of the secondary crucible has been mounted in the holder I1. Since the primary crucible 32 is open and unobstructed at its top the metal may be placed therein with facility, as will be clear.y After the metal has been placed in the .primary crucible, the upper section 22 of the secondary crucible is positioned upon the lower section 23 thereof, enclosing the primary crucible within the secondary crucible in the manner above stated, the flange I8 of the crucible. I9 cooperating with ange 35 of holder I1 to align the crucible sections 22 and 23, while restraining them against relative endwise movement and mounting the crucible as a whole upon the holder I1. After the crucible I9 has been charged with metal and properly mounted upon the holder I1, as above described, the metal within the crucible structure, preferably` Within the primary crucible 32, is melted preliminary to the casting operation. This metal may be melted in any suitable manner, though I preferably provide a high frequency inductionl coil 4B Ipositionable about the crucible structure I9 and removable therefrom to a position clear of the crucible structure and of the centrifugal casting machine parts which move during operation of the machine. The manner in which the induction coil 4U is positioned about and removed from the crucible I9 is not of the essence of my instant invention and that result may be accomplished in any suitable manner, though I preferably employ the means disclosed in my copending application for Centrifugal casting machine, filed January 20, 1945, Serial No. 573,745. Any means other than the induction coil 40 may be utilized for melting the metal in the crucible structure. Where the inr duction coil 40 is employed, upper section 22 of then set into operation. In the operation of the centrifugal casting machine, the molten metal is projected from the primary crucible 32 into gate 38 of mold 2D and thence into the casting cavity of the mold, as Ais knownin the centrifugal casting art. The outwardly tapering outer en d portion of the melting chamber 24 of the crucible structure assures that any metal which may be discharged from the primary crucible 32 before it reaches the outer end of neck 33, such as metal being crowded out of the open top of neck 33, will be projected into the mold. In the event of cracking or breaking of the primary Crucible 32 during the casting operation, molten metal leaking therefrom will pass into the recess in lower section 23 of the secondary Crucible and will be discharged therefrom between ribs 3| to discharge opening 25, and thence projected into the gate 38 of mold 20. That guards against loss of metal or interruption of the casting operation in the event of breakage or cracking of the primary Crucible, and the ange 29 and shoulder 30, previously referred to, further guard against loss or spillage from the Crucible structure I9 of molten metal which may leak or be discharged from the primary Crucible during the casting operation. The yprimary Crucible and the secondary Crucible thus cooperate to provide a Crucible structure which guards against excessive heating and cracking of the secondary Crucible, while assuring proper discharge of the molten metal from the Crucible structure into the mold and providing an inexpensive primary crucible which may readily be replaced without incurring objectionable expense.

I claim:

1. In a Crucible structure for use in centrifugal casting, a refractory body formed in two separate superposed interiorly recessed sections defining a melting chamber, said body having a restricted opening leading through its cuter end from said chamber, and an open topcrucible seating in the recess of the lower one of said sections having a restricted discharge neck extending through said opening, said body having integral inwardly projecting end walls restraining said Crucible against endwise movement relative to said body.

2. In a Crucible structure for use in centrifugal casting, a refractory body comprising a lower substantially semi-cylindrical section recessed from its upper face and a removable substantially semi-Cylindrical upper section seating on said lower section, said body having a restricted opening leading through its outer end from the recess of said lower section, and an open top Crucible removably seating in the recess of said lower section having a restricted discharge neck extending through said opening, said sections of said body having integral inwardly projecting end Walls restraining said Crucible against endwise movement relative to said body.

3. In a Crucible structure, a refractory body comprising a lower substantially semi-cylindrical section recessed from its upper face and an upper substantially semi-cylindrical section seating on said lower section, said body being disposed with its axis substantially horizontal and having a restricted opening leading through its outer end from the recess of said lower section and the latter section having interior spaced ribs extending generally lengthwise of the recess thereof, and an open top Crucible in the recess of said lower section seating on said ribs spaced thereby from the surrounding wall of said lower section, said Crucible having a restricted discharge neck extending through said opening and spaced from the bottom thereof, said sections of said body having integral inwardly projecting end walls restraining said Crucible against endwise movement relative to said body.

4. In a Crucible structure, a refractory body formed in two separate superposed substantially semi-cylindrical intertting interiorly recessed sections defining a melting chamber and a discharge opening leading therefrom through the outer end of said body adapted for reception of an open top Crucible seating in said Chamber having a restricted discharge neck extending through said opening, said sections having interfitting elements at their opposed faces restraining them against relative transverse and lengthwise movement and being provided at their outer ends with registering exterior elements adapted for interengagement with aligning and supporting flanges of a supporting structure eifective in Cooperation therewith for restraining said sections against relative endwise movement.

5. In a Crucible structure, a refractory body Comprising a lower substantially semi-cylindrical section dening an upwardly-opening substantially semi-cylindrical recess tapering upward and laterally inward at its outer end portion provid ing a restricted opening through its outer end, said lower section having interior lengthwise ribs extending into said outer tapered portion thereof, an upper substantially semi-cylindrical section removably seating on said upper section, and an open top Crucible substantially conforming to the interior of said lower section disposed within the latter seating on said ribs and extending into the outer tapered portion of said recess and open at its outerend, said body having integral end walls extending radially inward thereof restraining said Crucible against endwise movement relative to said body.

JOHN FREI, J n.

REFERENCES CITED The following references are of record in the le oi this patent:

UNITED STATES PATENTS 

